RE: [PATCH][2.4] generic cluster APIC support for systems with m ore than 8 CPUs

["Martin J. Bligh" <mbligh@aracnet.com>]

> I actually meant interrupt distribution (rather than interrupt routing).
> AFAIK, interrupt distribution right now assumes flat logical setup and
> tries to distribute the interrupt. And is disabled in case of clustered
> APIC mode.  I was just thinking loud, about the changes interrupt
> distribution code should have for systems using clustered APIC/physical
> mode (NUMAQ and non-NUMAQ).

Oh, you mean irq_balance? I'm happy to leave that turned off on NUMA-Q
until it does something less random than it does now. Getting some sort
of affinity for interrupts over a longer period is much more interesting
than providing pretty numbers under /proc/interrupts. Giving each of
the frequently used interrupts their own local CPU to process it would
be cool, but I see no purpose in continually moving them around. If you're
concerned about fairness, that's a scheduler problem to account for and
deal with, IMHO.

The provided topology functions should be able to do node_to_cpumask
and cpu_to_node mappings once that's sorted out. Treat each node as a
seperate "system" and balance within that.

M.